1. Field of the Invention
The present invention relates in general to a semiconductor memory device and, more particularly, to a semiconductor memory device and a method for writing and reading data to and from the same.
2. Description of the Related Art
A general semiconductor memory device inputs data from an external source, and outputs internally generated data through data input and output pins. Accordingly, the general semiconductor memory device could not perform data writing operations and data reading operations simultaneously.
Some general semiconductor memory devices have data input pads and data output pads formed separately. However, these kinds of devices do not transmit data through the data input pads and the data out pads simultaneously. That is, the data write lines and data read lines in the semiconductor memory device are not separated but constituted commonly like a semiconductor memory device in which data input pads and data output pads are adapted to be used commonly.
Accordingly, a conventional semiconductor memory device could not perform data input operations through data input/output (input) pads and data output operations through data input/output (output) pads simultaneously.
In order to enhance a bus efficiency of a system including semiconductor memory devices, it is necessary to provide a semiconductor memory device which performs data input and output simultaneously.